CCT-diagrams of Si-Mn-Mo system bainitic steel have been determined.With Mo 0.25%, the high-temperature transformation of the steel shifts large to the right,and the bainitic transformation becomes a "flat topped C-curve" at cooling rate in widerange. Si in the steel may cause a shift of the bainitic transformation region towards the right,and of the pro-eutectoid ferritic transformation region towards the left. Mn may delay thehigh temperature transformation more violently than the bainitic transformation.

In situ eutectic Al_(11)La_3 / Al composite material with regular orientation wasprepared by zone melt liquid metal cooling equipment of directional solidification under con-dition of high temperature gradient 700 K / cm and growth rate 6.0-20.0μm/s. Superposediffraction pattern of Al_(11)La_3/Al composite shows that preferred growth direction is(100)Al / (331) Al_(11)La_3, and habit plane is (002)Al/(116)Al_(11)La_3. A low density (103) twinis observed in Al_(11)La_3 and the growth of (103) twin induces to branching to change theinterlamellar spacing.

The profile features of solidifying interface of irregular Al-Si eutectic duringdirectional solidification were studied by solving a nonlinear coupling equation of directionalsolidification of Ai-Si eutectic. The critical splitting point of the solidifying interface coin- cides with the maximum value of its position and corresponds to the marginal stability point.Argument is presented that the interlamellar spacing for local regular structure selects the crit-ical splitting state of α(Al)-liquid interface as its operating point, and the operating point ofaverage interflake spacing for irregular structure is the critical splitting state of β(Si)-liquidinterface. The scaling laws derived, which have more general forms than the classicJackson-Hunt scaling, gained support from the experimental results.

The statistically significant experimental technique was developed to investi-gate the directional solidification behavior of a nickel-base superalloy. This technique in-volves quantitative description of the rough level of the solid/liquid interface by means offractal analyses. The image analysis system technique was employed and the fractal dimensionof the solid / liquid interface of the test alloy was obtained. The relations among the fractal dimensions of the solid / liquid interface, solidification rate, dendrite arm spacing and thephosphorus content in the test alloys have been given. It was found that the increases of thesolidification rate and the phosphorus content in the test alloy will lead to increasing fractaldimension of the solid / liquid interface with index law. Furthermore, combining the fractaltheory and the thermodynamic principle with the measured results, it has been proved that thefractal dimension is far from simple geometrical parameter used in describing irregular geom-etry. It is a state function which depends on different physical parameters.

In rapidly solidified Ni-34.6 at-%Al alloy, when cooling rate duringsolidification reached the order of 10~6K/s, the size of the microstructures, such as grain andsubstructure of the martensite, decreased dramatically. The various kinds of interfaces withhigh density and homogeneous distribution resisted effectively the propagation of the cracksand resulted in localized plastic deformation ahead of the tips of microcracks. The ductilityand toughness at room temperature of the Ni-rich NiAl may be improved considerably.

Effect of laser scanning speed on phase constitution, microstructure,microhardness and wear resistance of laser-cladding stellite hard facing alloy by using of across-flow-stype CO_2 laser of power 1. 5 kW has been investigated. The laser-cladding layeron the alloy consists of matrix phase of over-saturation solid solution γ(Co, Cr) and complexhexagonal carbide M_7C_3. Under certain condition, with fast laser scanning speed, the oversaturation solubility of elements increases in γ(Co, Cr), and the precipitation of the complexcarbide M_7C_3 decreases, so that the microhardness increases and the wear resistance de-creases. But at slower laser scanning speed, more complex carbide M_7C_3 may precipitate, andthe wear resistance may be improved. Therefore, it is believed that the principal factor in im-provement over wear resistance is the precipitation of carbide M_7C_3, while overmicrohardness is the over-saturation solubility of elements in matrix phase (Co, Cr).

Studies were made of the effect of tempering varied at temperature rangedfrom 25 to 750℃ for 0.5 to 100 h on the changes of measured hardness, precipitated phaseand its alloying elements content as well as the activation energy of tempering for quenchedsteel 20Cr11MoVNbNB. Tempering of the steel below 400℃ may be controlled by diffusionof C atoms in α-Fe, and over 400℃, by diffusion of Cr, also Mo or V, in α-Fe

The solubilities of Ce, Nd and Y in α-Fe at 873 to 1153K have been determined by means of electron microprobe quantitative analyses. The temperature dependencesof the solubilities were obtained from the experimental data. The results have been comparedwith those determined by three other technigues, very good agreement was obtained betweenthe results of all these techniques.

Determination was carried out of fatigue crack propagation rate of steel65Cr5Mo3W2VSiTi (LM2) with various bainite contents and M/B duplex structure tem-pered at various temperatures. The threshold value of fatigue for each processing was esti-mated by experimental data. The mechanism for fatigue crack propagation of M / B duplexstructure in steel LM2 seems to be non-continuous. Both calculated and measured fatiguecrack micro-propagation rates are found to be matched.

Based on theoretical calculation of electronegativity of groups offlotation-reagent and method of infra-red adsorption spectroscopy, the collection andadsorption of α-nitroso-β-naphthol in hematite flotation have been studied. The chemicaladsorption seems to be predominant owing to formation of pentacyclic nitrosyl chelate com-pound by atoms of nitrosyl bond in α-nitroso-β-naphthol together with Fe~(3+) on hematitesurface. Meanwhile, the non-uniform multi-layer physical adsorption is also occurred.

With the aid of 3-dimensional topological analysis methodology, relation-ships among phase regions on the isotherm section of the Nd-Fe-B phase diagram at 1000℃and those on vertical sections of the Pr-Fe-B phase diagram passing through Pr_2Fe_14B pointhave been re-discussed and modified.

The molten NaF-CaF_2 system has been studied by molecular dynamicssimulation. The pair correlation functions between cations and anionsand the bond angle dis-tributions of cation and anion triplets have beenobtained. The bridging and complexing in thesystem are discussedbased on the pair correlation functions and bond angle distributions.Theresults simulated show that the F~- ions around Ca~(2+) ion do not form tetrahedroncoordination, so that some of small complexing clusters such as CaF_4~(2-) are hardly found. Apossible structure of F~-; ions around Ca~(2+) ions is that three Ca~(2+) ions consistute an equilat-eral triangle through three Ca-F-Ca bridges and two F~- ions are located over and under thecenter of the right triangle, respectively. Meanwhile, on the outside of the triangle, everyCa~(2+) ion has another two F~- ions as its neighbor.

Effect of a sputtered Co-30Cr-5Al microcrystalline coating on oxidation re-sistance of TiAl intermetallic compound and oxidation behaviour of the bare TiAl compoundwere studied at 900-1000℃ in static air. The oxidation kinetics for the TiAl alloy seems toapproximately follow a linear rate law. Poor oxidation resistance of TiAl is due to the forma-tion of the mixed Al_2O_3 +TiO_2 scale which is loosely packed and easily spalled off but not ofdense and adherent unique Al_2O_3. A sputtered Co-30Cr-5Al coating, 30μm thick, can re-markably improve the oxidation resistance of TiAl owing to formation of adherentAl_2O_3 protective layer. However, many Kirkendall voids were formed between coating andsubstrate.

The hardness and wear resistance of sprayed FeBSi coating after laser remelt-ing were much improved by addition of 8% CeO_2. Microstructural observation on theFeBSi+CeO_2 coating revealed that the formation of martensite occurs, as well as the refinedgrains and the more eutectics and compounds with regular morphology are distributed. Whilethe FeBSi coating free from CeO_2 is a sharp constrast in microstructure.

High coercive Sm-Fe-N permanent magnet of _iH_c=33.1 kA/cm and(BH)_(max)=98.7kJ/cm~3 was prepared by mechanical alloying together with proper heattreatment and nitriding using pure Sm and Fe powders. It is believed that the mechanical al-loying by high power ball milling and the grain size down to about tens of nm are most effi-cient approach to prepare such magnet. The occurrence of some soft magnetic phases seemsto lead to the shoulder on the demagnetization curves.

Samples of R_2Fe_(17)N_x(R=Y, Dy, Nd) were measured by neutron diffraction,and their magnetic structures and N site were determined. The effect of the site occupation ofN on magnetic properties was discussed primarily.

A new technique of centrifugal casting was firstly provided withelectromagnetic field. Taking a heat resisting alloy steel 25Cr20Ni and an Al-Cu alloy as ex-amples,products, though their length,diameter and wall thickness are varied, revealed so supe-rior macrostructures that the mechanical properties are much improved in comparison withconventional centrifugal casting.

From solving the nonlinear equation of thermal conduction by using the finitedifference method,the effects of temperature rise in metals during high currention-implantation have been calculated. Curves of temperature rises, curves of profile temper-ature distributions, and dependences of sample surface temperature upon ion energies,doserates, target temperatures, and sample thicknesses are obtained. The processes of temperaturerise in pulsed and scanning ion-implantations are computed as well, and the temperaturefluctuations in them are discussed also.